Optical-electronic rangefinder

Abstract

There is provided by the present invention an optical-electronic rangefin having a housing adapted to be integrated in the gripping arm or mechanism of a robot and housing a light transmitter transmitting a well focussed high intensity light beam, a light receiver having a position detector, a pulse-electronic circuit for controlling the light transmitter and an amplifier circuit for transforming the currents received from the position detector into proportional voltages. The light transmitter and light receiver are so disposed with respect to each other that the central axis of the light transmitter and the optical axis of the light receiver define a predetermined acute angle between each other.

What is claimed is: 
     
       1. A circuit arrangement for processing voltages on the output of a light transmitter of an optical-electronic rangefinder, said rangefinder including a light transmitter in the form of a CW laser diode transmitting a well focussed high intensity light beam, a light receiver having a position sensitive detector, the central axis of the light transmitter and the optical axis of the light receiver defining a predetermined acute angle therebetween, a pulse-electronic circuit for controlling the light transmitter and an amplifier circuit for transforming the currents received from the position detector into proportional voltages, said circuit arrangement comprising two high pass filters in two separate channels for converting the output currents of the position detector in the light receiver into measuring light voltages, said channels each having means for offset and drift compensation and an after-connected sample hold block, a dividing unit for dividing the difference of said measuring light voltages formed in a difference amplifier by the sum of said measuring light voltages formed in a sum amplifier, and a low-pass filter and an analog-digital converter for applying said quotient to a look-up chart, said look-up chart supplying the value of the range. 
     
     
       2. The circuit arrangement as defined in claim 1, wherein the output voltages of said high-pass filters are applied as input voltages of the means for offset and drift compensation on the one hand to a first input of a sum amplifier and a second sample hold block and on the other hand directly to a difference amplifier having its output in each channel applied to a filter inversed to said high-pass filters, the output of said filter being applied on he one hand to a second input of the sum amplifier and on the other hand to the after-connected sample hold block. 
     
     
       3. The circuit arrangement as defined in claim 1 which further comprises means for controlling the pulse intensity of the CW laser diode, said means including two level detectors, an OR-member, a 4-bit counter and a digital-analog converter, wherein the output voltages of the sample hold blocks and the filter output voltages of the means for offset and drift compensation are precessed further by the level detectors and the OR-member to the cycle-controlled counter and thereafter to the digital-analog converter to form a voltage for controlling the CW light-emitting diodes. 
     
     
       4. The circuit arrangement as defined in claim 1, wherein said light transmitter laser diode is optically coupled with a photodiode and has a highly refracting microlens with a short focal length as well as apertures afterconnected to the laser diode for focusing the divergent radiation transmitted by the laser diode and wherein the flow of current through the laser diode and proportionally thereto the current of the photodiode optically coupled with the laser diode is controlled by means of a circuit consisting of a difference amplifier and a field effect tansistor afterconnected to the amplifier so as to increase the range of output of the laser diode. 
     
     
       5. The circuit arrangement as defined in claim 4, wherein the output voltages of said high-pass filters are applied as input voltages of the means for offset and drift compensation on the one hand to a first input of a sum amplifier and a second sample hold block and on the other hand directly to a difference amplifier having its output in each channel applied to a filter inversed to said high-pass filters, the output of said filter being applied on the one hand to a second input of the sum amplifier and on the other hand to the after-connected sample hold block. 
     
     
       6. The circuit arrangement as defined in claim 4, which further comprises means for controlling the pulse intensity of the CW laser diode, said means including two level detectors, an OR-member, a 4-bit counter and a digital-analog converter, wherein the output voltages of the sample hold blocks and the filter output voltages of the means for offset and drift compensation are processed further by the level detectors and the OR-member to the cycle-controlled counter and thereafter to the digital-analog converter to form a voltage for controlling the CW light-emitting diodes. 
     
     
       7. An optical-electronic rangefinder adapted for mounting in the gripping arm of a robot, comprising: a housing adapted to be integrated in the gripping arm of a robot;   two arrangements of two parallel rangefinding systems each are provided in said housing;   each of said two parallel rangefinding systems including a light transmitter having a light emitting diode and transmitting a well focused, high intensity light beam and having a pulse electronic circuit;   a light receiver associated with each of said two parallel rangefinding systems having a position-sensitive-detector disposed in said housing, each of said two parallel rangefinding systems being arranged symmetrically with respect to the central axis of the respective position-sensitive-detector;   two lens systems associated with each position-sensitive-detector, said lens systems being arranged with a corresponding angle relative to each other; and   an amplifier circuit disposed in said housing for transforming the currents received from the position-sensitive-detector of the light receiver of each arrangement into proportional voltages;   said two arrangements of two parallel rangefinding systems being disposed at right angles with respect to each other so that the paths of the rays of the light transmitters and of the light receivers are entwined with each other.   
     
     
       8. The optical-electronic rangefinder as defined in claim 1, wherein said light transmitters are GaAlAs-CW laser diodes optically coupled with photo diodes, and having a highly refracting microlens with a short focal length as well as apertures afterconnected to said laser diodes for focusing the divergent radiation transmitted by said laser diodes, and a circuit consisting of a difference amplifier and a field effect transistor afterconnected to said amplifier for controlling the flow of current through the laser diodes and proportionally thereto the current of the photo diodes optically coupled with said laser diodes in order to increase the range of output of the laser diodes. 
     
     
       9. The optical-electronic rangefinder as defined in claim 8, wherein a nonlinear counter coupling circuit is provided between the output of the difference amplifier and its negative input so as to stabilize the output of the laser diode. 
     
     
       10. The optical-electronic rangefinder as defined in claim 9 wherein in said counter coupling circuit, a Zener diode and a resistor are connected in series between the output of the difference amplifier and ground, and capacitor is connected between the connection between the Zener diode and the resistor and the negative input of the difference amplifier. 
     
     
       11. An optical-electronic rangefinder adapted for mounting in the gripping arm of a robot, comprising: a housing adapted to be intergrated in the gripping arm of a robot;   two arrangements of two parallel rangefinding systems each are provided in said housing;   each of said two rangefinding systems comprising a laser diode as a light transmitter transmitting a well focused, high intensity light beam and having a pulse electronic circuit;   a light receiver associated with each of said two parallel rangefinding systems having a position-sensitive-detector disposed in said housing, each of said two parallel rangefinding systems being arranged symmetrically with respect to the central axis of the respective position-sensitive-detector;   two lens systems associated with each position-sensitive-detector, said lens systems being arranged with a corresponding angle relative to each other; and   an amplifier circuit disposed in said housing for transforming the currents received from the position-sensitive-detector of the light receiver of each arrangement into proportional voltages;   said two arrangements of two parallel rangefinding systems being disposed at right angles with respect to each other so that the paths of the rays of the light transmitters and of the light receivers are entwined with each other.   
     
     
       12. The optical-electronic rangefinder as defined in claim 17, wherein said light transmitters are GaAlAs-CW laser diodes optically coupled with photo diodes, and having a highly refracting microlens with a short focal length as well as apertures afterconnected to said laser diodes for focusing the divergent radiation transmitted by said laser diodes, and a circuit consisting of a difference amplifier and a field effect transistor afterconnected to said amplifier for controlling the flow of current through the laser diodes and proportionally thereto the current of the photo didoes optically coupled with said laser diodes in order to increase the range of output of the laser diodes. 
     
     
       13. The optical-electronic rangefinder as defined in claim 12, wherein a nonlinear counter coupling circuit is provided between the output of the difference amplifier and its negative input so as to stabilize the output of the laser diode. 
     
     
       14. The optical-electronic rangefinder as defined in claim 13, wherein in said counter coupling circuit, a Zener diode and a resistor are connected in series between the output of the difference amplifier and ground, and a capacitor is connected between the connection between the Zener diode and the resistor and the negative input of the difference amplifier.